The invention relates to a finger lever of a valve drive of an internal combustion engine, which can be switched to different lifts for at least one gas-exchange valve and which comprises an outer lever and an inner lever running between its arms and moving in a pivoting motion relative to this outer lever, with a borehole extending in the longitudinal direction of the lever being applied with a piston to one end of one of the levers, wherein this piston can be displaced with its top side in some sections under a driving surface of one end of the other respective lever, so that when coupled a large valve lift is generated, and when uncoupled a small or 0 valve lift is generated, wherein on the bottom side of the finger lever, a contact for a gas-exchange valve is provided on one end and a complementary surface for a support element is provided on the other end and wherein a force can be applied by at least one large lifting cam on a top side of at least the lever pivoting away in the decoupled case.
A finger lever defining this class is disclosed in DE 103 18 295 A1. Its piston extends as a coupling means in a borehole at one end of the inner element and can be displaced for the coupled case in some sections under a correspondingly shaped complementary driving surface of a crossbar of the outer lever.
The geometry of the coupling (convex in concave) and also production-specific inaccuracies or function-dependent play can lead to so-called “edge supports” during the operation of the cam follower in the coupled case. These are undesirable primarily because one inlet or outlet side edge of the driving surface becomes the main support surface when coupled. These elevated and undesired contact pressures can lead to an impact in the coupling area, so that, in turn, the play of the coupling is increased. However, this play must be held within tight tolerance limits, in order to guarantee proper functioning of the valve drive over its service life. Under some circumstances, the previously mentioned “edge supports” can also lead to the production of shavings, which can lead to the seizing of the respective piston.